Structural Change of Ni Species in Ni/SiO2 Catalyst during Decomposition of Methane

Tanaka, Sakae; Ogihara, Hitoshi; Otsuka, Kiyoshi

doi:10.1006/jcat.2002.3523

Cited by 114 publications

(68 citation statements)

References 26 publications

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“…Catalytic gasification, CNT and CNF growth, and catalytic graphitization presumably involve a similar general mechanism of carbon atoms dissolutions, diffusion and precipitation from the catalyst Ni particles [56,65]. However, several works have claimed the presence of dissolved carbon [44,82] or carbide-like compounds [81] in Ni catalyst particles after CNF growth. Such dissolved carbon or carbon contamination has also been reported in works involving metal catalyst supported on non-graphitic carbons [1,83,84].…”

Section: The Effect Of the Subsequent Treatment To The Cnf/ac Compositementioning

confidence: 99%

Controlling the yield and structure of carbon nanofibers grown on a nickel/activated carbon catalyst

Rinaldi

Abdullah

Ali

et al. 2009

Carbon

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Carbon nanofibers (CNFs) were grown via the chemical vapor deposition of C2H4 on an activated carbon (AC)-supported Ni catalyst. The texture of the CNF/AC composites can be tuned by varying the growth temperature and by treatment in reducing atmosphere prior to C2H4/H2 exposure. The Ni-catalyzed gasification of the AC support increases the microporosity of the composite and shown to be dominant throughout the composite synthesis especially during reduction, subsequent treatment in reducing atmosphere, and CNF growth at low temperatures. N2 isotherm and scanning electron microscope were used to characterize the texture and morphology of the composites. Subsequent treatment in reducing atmosphere were shown to increase the Ni catalyst activity to grow CNFs. High resolution transmission electron microscope however did not reveal any microstructural difference for Ni catalyst with and without the subsequent reduction treatment. We propose in this paper that the carbon dissolutions during treatment of the catalyst might have an implication on the CNF growth.

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Section: The Effect Of the Subsequent Treatment To The Cnf/ac Compositementioning

confidence: 99%

Controlling the yield and structure of carbon nanofibers grown on a nickel/activated carbon catalyst

Rinaldi

Abdullah

Ali

et al. 2009

Carbon

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“…As a result, the initial sizes of the catalyst particles do not necessarily determine the diameter of the CNFs. [10,11,14] Table 4 shows the textural parameters of the CNFs. Figure 8 shows the XRD spectra of CNFs growth on catalysts produced at different calcination temperatures.…”

Section: Structure Of the Cnfsmentioning

confidence: 99%

“…[10,11,14] It is generally observed that a metal particle is at the tip of CNFs during reaction and that the diameter of the CNFs is approximately identical to the diameter of the metal particle. Kukovitsky [14] found that at a low temperature (700…”

Section: Introductionmentioning

confidence: 99%

Catalytic decomposition of methane over supported Ni catalysts with different particle sizes

Sun

Sui

Zhou

et al. 2009

Asia-Pacific J Chem Eng

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Methane decomposition on γ -Al 2 O 3 -supported Ni catalysts, as a method for the production of carbon nanofibers (CNFs) and CO-free hydrogen, has been investigated to show the effect of catalyst particle size on the rate and yield of CNFs formation. The catalysts were prepared by deposition-precipitation with different calcination temperature ranging from 725 to 1025 K so as to have different initial particle sizes. The results show that catalysts with smaller initial particle sizes had higher initial growth rate but experienced fast deactivation. The lifetime of the catalyst, ending at the inflection point on the rate curve of CNFs growth, could well represent the yield of CNFs of the catalyst, and the maximal yield of CNFs was achieved on the Ni catalysts calcinated at 823 K and with a particle size of around 56 nm. However, the diameters of the grown CNFs were not directly related to the initial size of the catalysts, because of particle sintering and breaking during catalyst reduction or CNFs formation. 

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“…Catalytic decomposition of methane over Ni catalysts is an effective method for CNFs synthesis and also an alternative route of hydrogen production from natural gas (Takenaka et al, 2002(Takenaka et al, , 2003a(Takenaka et al, , 2003b. This reaction is moderately endothermic: carbon growth in steam or dry reforming of methane process.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Vapor Decomposition of Methane over Nickle Catalyst: Growth Rate and the Corresponding Microstructures of Carbon Nanofibers

Sui

Sun

Zhou

et al. 2009

J. Chem. Eng. Japan

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Time-resolved intrinsic reaction rate of catalytic vapor deposition of methane into carbon nanofibers (CNFs) and hydrogen on supported Ni catalysts was determined under different reaction temperatures (773-973 K) and feed compositions (P H 2 = 0 P H 2 = 0 P H 2 = 0-0.29 atm, P CH 4 = 0.28 P CH 4 = 0.28 P CH 4 = 0.28-0.71 atm) and the microstructure of the produced CNFs was characterized by Raman and TEM. The results showed that, increasing the reaction temperature, methane partial pressure and decreasing hydrogen partial pressure increased the initial reaction rate but generally led to fast catalyst deactivation. A high carbon yield per unit catalyst was obtained as a compromise between initial reaction rate and catalyst deactivation rate. The microstructures of the produced CNFs had a close relationship with the initial reaction rate. The CNFs produced with high initial rate tended to have a small angle between the graphene layers and the growth axis, thin diameter and a hollow core. This phenomenon can be used for monitoring and controlling the CNFs synthesis process.

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Structural Change of Ni Species in Ni/SiO2 Catalyst during Decomposition of Methane

Cited by 114 publications

References 26 publications

Controlling the yield and structure of carbon nanofibers grown on a nickel/activated carbon catalyst

Controlling the yield and structure of carbon nanofibers grown on a nickel/activated carbon catalyst

Catalytic decomposition of methane over supported Ni catalysts with different particle sizes

Catalytic Vapor Decomposition of Methane over Nickle Catalyst: Growth Rate and the Corresponding Microstructures of Carbon Nanofibers

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